Studies of the Hong Kong Influenza Hemagglutinin

Abstract

An influenza virus consists of a transcriptase complex surrounded by a lipid membrane. Each complex contains eight RNA molecules, which make up the virus genome in association with polypeptides of five different types, members of at least three of which participate in transcriptase activity. The virus membrane is derived from the surface membrane of the infected cells, from which the assembled virus is released by a process of membrane budding. During infection, this membrane is modified to contain two types of virus-specified glycoproteins, the hemagglutinins (about 500–1000 per virus) and the neuraminidase molecules (about 100–500 per virus). The more abundant hemagglutinin is the glycoprotein that interacts with infectivity-neutralizing antibodies.1 Because of the hemagglutinin’s consequent importance in antigenic variation, its structure and antigenicity have been analyzed in detail. In this chapter, we will describe a number of the applications of antihemagglutinin monoclonal antibodies in these studies. We will concentrate on the hemagglutinins of viruses of the H3 antigenic subtype, the Hong Kong influenza viruses, primarily because detailed information on the three-dimensional structure of a hemagglutinin is at present only available for the hemagglutinin of the 1968 Hong Kong virus.